Adjustable igniter for oil burners



Sept. 19, 1950 J. A, WILSON ADJUSTABLE IGNITER FOR OIL BURNERS Filed May 8, 194a INVENTOR. John A. Wilson JM 1 WW ATTORNEYS Patented Sept. 19, 19 50 ADJUSTABLE IGNITER FOR OIL BURNERS John A. Wilson, Detroit, Mich., assignor to The Timken-Dctroit Axle Company, Detroit, Mich a corporation of Ohio Application May 8, 1946, Serial No. 668,302 6 Claims. (01. 175-115) This invention relates generally to fluid fuel burners of the rotary wall flame type and more specifically to the ignition system thereof.

\ In burners of this type droplets of fluid fuel from a rotating fuel head are projected or sprayed against a metal flame rim at the periphery of the combustion chamber where they are vaporized and admixed with air and the mixture ignited. Ignition is efiected by an electric spark crossing a gap between the conductive metal flame rim which serves as one electrode and another suitable electrode which is insulated from the flame rim but located at the flame rim. Usually only one spark gap is needed in each burner, but two or more may be provided if desired.

It has been determined that the length of the spark gapand its location relative to the level of the trajectory of the oil droplets are very important factors in obtaining efficient combustion. Hence, it has been found necessary to carefully position the insulated electrode with respect to the flame rim and one of the hitherto suggested constructions for attempting to properly position the spark gap is disclosed in United States Letters Patent to Wilson et al. No. 2,220,858, and the present invention is an improvement over that arrangement.

In such burners, the actual spark gap distance is determined by rotative adjustment of the insulated electrode with respect to the flame rim, and the vertical location of the spark gap is determined by vertical positioning of the insulated electrode. Installation workers have found that in prior burners these adjustments were difficult to correlate, especially when a worker tried to hold the rotative adjustment steady while setting the height adjustment of the electrode.

Adjustment of the spark gap position and spacing in such burners is particularly rendered diflicult due to the fact that the adjustable electrode is located well within the combustion chamber which has only a relatively small accessdoor, and the adjustments are located below the hearth. Electrode adjustment mechanism within the combustion chamber is undesirable. and impractical because all parts of such mechanism would have to be constructed in such a manner as to withstand the intense heat in the .combustion chamber when the burned apparatus is in operation, which is expensive, or otherwise the heat would tend to warp and otherwise change the physical properties of the parts of the adjustment mechanism.

, 2 It has also been the practice in the past to predetermine the position of the spark gap and to permanently fix the electrode in this predetermined location at the initial assembly of the burner apparatus. This procedure has led to continuous misalignments due to manufacturing tolerances and errors and also due to the fact that different heating conditions require slightly varied spark gap spacings and positions to obtain the maximum efficiency of the burner apparatus.

It is therefore the major object of the presentinvention to provide novel arrangements for accurately and speedily setting and/or adjusting the length and position of the spark gap in a rotary wall flame burner.

A further object of this invention is to provide a novel vertical adjustment for a fluid fuel burner electrode, located in the space below the combustion chamber so as to be remote from the intense heat of the combustion chamber, coupled with an arrangement for holding the electrode against rotation during such vertical adjustment.

Another object of this invention is the provision of a simple removable tool which will interchangeably fit with a number of igniter assemblles in fluid fuel burning apparatus, and is adapted to retain an electrode thereof in a desired radial position determining a particular spark gap length while the electrode is vertically adjusted and locked in position.

A further object of the invention is to provide a novel ignition electrode holder for an oil burner or the like.

These and other objects will become apparent as the specification proceeds in connection with the appended claims and the annexed drawings,

wherein: 3

Figure 1 is an elevation in partial section Figure 2 showing further the electrode adjust-=, ment guide of this invention;

Figure 4 is a top plan fragmentary view of the, electrode assembly illustrating rotative adjustment of the electrode; and

Figure 5 is a perspective view of the tool that I The specificaton proceeds with continued reference to the drawings wherein like reference numerals designate the same parts throughout the several views.

Referring to Figure l, a vertical wall 2 provided with lugs 4 supports a suitable hearth pan 5. A hearth 8 of a suitable refractory material is disposed upon hearth pan 6 and serves as a partition between an upper combustion chamber I and the chamber 2 adjacently beneath in which is installed a motor assembly Hi for rotating the fuel head comprising tubes It and fan |8 disposed within the said combustion chamber.

A transformer 2|! is mounted in chamber i2 on a suitable base 22 directly beneath motor I4. A suitable sheet metal annular flame rim 24 having an upright oil impingement wall 25 is seated on hearth 8, and a circular aperture 21 is provided in hearth 8 adjacent the flame rim for accommodating an ignition electrode holder designated at 28 and made of a hard electrical insulation material such as porcelain.

Electrode holder 28 is embraced by a split collar 29 which has its ends secured together by a fastening screw or like assembly 39. A right angle bracket 3|, which-is preferably integral with collar 29 and fixed as by spot welding to a rigid metal plate 32 securely imbedded in the bottom surface of hearth 8, supports the ignition electrode assembly on hearth 8.

A sheet metal strap 33, having its upper end disposed beneath the bottom of flame rim 2% and preferably spot welded thereto to establish electrical contact, is bent to extend downwardly through aperture 2? and traverse the inner periphery of collar 23. A set screw and lock washer assembly 34 secures strap 33 to collar 29 and is usually held against accidental displacement by contact of its head with electrode holder 23 when screw 30 is tight. A terminal post assembly 35 on the lower end of strap 33 is thus electrically connected to the flame rim 24.

Electrode holder 28 comp-rises a porcelain body 36 having a central bore 3'1 slidably and rotatably receiving the vertical shank 38 of a metal rod electrode 39. Bore 3'! opens upwardly to an enlarged cup-shaped recess/4| which tapers so as to be larger at its upper end than at the bottom. A metal band 42 rigid with strap 33 surrounds the upper end of body 36' within aperture 21.

The lower end of bore 3? opens into an enlarged recess 43 wherein an electrode guide and adjustment device 4 is rigidly secured as by a suitable adhesive 45. Device 44 preferably comprises a pair of welded together sheet metal plates formed with mated half-cylindrical portions to provide a tubular vertical guide 46 and having laterally extending wings fitting into slots 4'1 of the holder body so as to further inhibit rotation of the device on the holder.

The device is formed with an aperture intermediate the ends of tubular guide d5 of a size to accommodate and allow rotation of a knurled nut 48 on the threaded end 49 of shank 38. R0- tation of nut 48 thus provides axial displacement of shank 38. A wing nut 5| is employed to lock the electrode in a desired adjusted position as will appear and also for mounting thereon a spring terminal clip 52 for attachment of a transformer lead 53. The other transformer lead 54 is attached to terminal post 35.

At its upper end, rod electrode 39 terminates in a radially extending tip 55 which as illustrated in Figure 4 extends to a point adjacent flame rim wall 25 to form a spark gap therewith designated at S in Figure 4. Asalso seen in Figure 4, rotation of electrode 39 about its axis varies the length of spark gap S.

It has been determined that the igniter assembly functions most efficiently when the spark from electrode 39 contacts the flame rim wall 25 substantially at the level where the projected droplets or fuel impinge upon that wall. This setting is made by vertical adjustment of the electrode by rotation of nut 48 which is held against vertical displacement.

Rotation of electrode 28 about its vertical axis to set the spark gap length correctly is accomplished as a first adjustment. Collar to rigid with electrode 39 determines the lowermost po- Sition of the electrode while permitting free rotation to set the spark gap. In order to maintain this correct spark gap length while the height of said electrode with relationship to the level at which the droplets of fuel oil impinge against the flame rim is being adjusted, the radial position of electrode 39 is maintained by the electrode looking or holding sleeve 58 best illuse trated in Figure 5.

Electrode holding sleeve 58 is a tool made of a relatively springy sheet metal or like material and is basically a cylindrical tube with a section of its wall removed in such a manner as to form a slot 59 running its full length. The slot, which is vertically disposed, is preferably made with a slight taper. The diameter of the sleeve is smaller than the large diameter of recess 4| but is larger than the small diameter of recess 4 With wing nut 5| loose and the electrode holder clamped in collar 29, the worker reaches into the combustion chamber and rotates the electrode to set the proper spark gap S. Then electrode adjusting sleeve 58 is inserted into tapered recess 4| of insulator body 36 with tapered slot 59 straddling the radially extending portion of electrode 39. The bottom extremity of said tapered hollow recess 4| has a slightly smaller diameter than the expanded diameter of sleeve 58, and the sleeve is' thereby compressed slightly as it is advanced to-v ward the bottom of the recess. The springiness of the material of which said sleeve is constructed causes a suiiicient frictional binding action between said sleeve and the walls of the recess to hold said sleeve in fixed position on insulator body 26.

It can therefore readily be seen that electrode holding sleeve 56 can lock the extremity of electrode 39 in any desired radial position while the electrode, due to. vertical slot 59, is free to be amoved up and down for vertical adjustment for locating electrode tip 55 in optimum position with respect to the oil spray impinging on the flame rim so that the oil may be readily ignited, The tapered slot of the electrode locating sleeve 58 permits the sleeve to be used on electrodes of different sizes.

After the correct radial position Qf electrode 39 is obtained and locked by sleeve 58, the cor-. rect height of tip 55 is then obtained merely by i= rotating adjusting nut 48. Wing nut 5| is then tightened, locking electrode 39 against either ro tational or vertical movement.

ready for operation when electrically connected to leads 53 and 54.

Adjustment according to the invention may be made during installation, or may be at any time later. It is particularly good for periodic servicing of the burner. A material advantage of this adjustment is that a single size electrode may be positioned for correct association with flame rims of different heights.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In an electrical ignition assembly wherein an electrode projects upwardly through a hearth with its tip disposed in accurate spark gap relation with respect to a metal flame rim, an electrode holder of hard electrical insulating material adapted to be mounted on said hearth and having a vertical bore for rotatably and slidably mounting a rod electrode, a rod electrode guide member fixed to the lower end of said holder, means on said guide member for adjusting the electrode axially of said bore and maintaining said adjustment for locating said electrode in its optimum vertical position with respect to said flame rim, and means on said electrode operable separabl from said adjusting means but coacting with said adjusting means for locking said electrode to said guide member.

2. In an ignition assembly, an electrode holder of hard insulating material having a bore for slidably and rotatably receiving a rod electrode, a, tubular guide member secured upon the bottom of said holder, the lower end of said electrode being threaded where it extends through said guide member and said guide member being recessed intermediate its ends, a rotatable nut mounted in said recess and threaded with said electrode so that upon rotation of said nut the latter is held against axial displacement and thereby shifts said electrode axially of said bore, and means on said electrode coactin with said nut and the guide member for locking said electrode against both rotation and axial displacement.

3. In an ignition assembly for a fluid fuel burner, a holder of hard electrical insulating material having a vertical through bore, a metal 6 rod electrode slidable and rotatable in said bore. a rod electrode guide member secured upon the lower end of said holder, means on said guide member for vertically adjusting said rod electrode axially of said bore and maintaining said adjustment, and means operable separately from said adjusting means but mechanically coacting with said adjusting means for positively locking the rod electrode against both rotation and axial movement in said bore.

4. In an ignition assembly for a fluid fuel burner,.a holder of hard electrical insulatin material having a vertical bore, a metal electrode rod slidable and rotatable in said bore, means on the lower end of said holder adjustablefor vertically displacing said electrode on said holder and maintainin said adjustment, and means separately operable from said adjusting means and comprising cooperating parts on said rod and said adjusting means for locking the vertically adjusted electrode against rotation in said bore, and said locking means comprising a nut threaded on the lower end of said rod adapted to seat upon the bottom of said sleeve.

5. In the ignition assembly defined in claim 4, said electrode adjustment means comprising a guide sleeve rigidly mounted on the bottom of said holder, and rotatable means on said guide sleeve operatively connected to said electrode rod. 1

6. In the ignition assembly defined in claim 5, said sleeve being metal and an electric wire terminal clip clamped between said nut and said sleeve.

JOHN A. WILSON. 1

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 564,151 Jacoby July 14, 1896 622,005 Herrick Mar. 28, 1899 1,247,328 Reams Nov. 20, 1917 1,887,230 Chandler Nov. 8, 1932 2,051,130 Cole Aug. 18, 1936 2,115,873 Powers May 3, 1938 2,162,572 Bock June 13, 1939 2,220,858 Wilson et al Nov. 5, 1940 

